We study the distribution of baryonic and luminous matter within the
framework of a hierarchical scenario. Using an analytical model for
structure formation which has already been checked against
observations for galaxies, Lyman-α clouds, clusters and reionization
processes, we present its predictions for the bias of these
objects. We describe its dependence on the luminosity (for galaxies or
quasars) or the column density (for Lyman-α absorbers) of the
considered objects. We also study its redshift evolution, which can
exhibit an intricate behaviour. These astrophysical objects
do not trace the dark matter
density field, the Lyman-α
forest clouds being undercorrelated and the bright galaxies overcorrelated,
while the intermediate class of
Lyman-limit systems is seen to sample the matter field quite well.
We also present the distribution of baryonic matter
over these various objects. We show that light does not trace baryonic
mass, since bright galaxies which contain most of the stars only form
a small fraction of the mass associated with virialized and cooled
halos. We consider two cosmologies: a critical density universe and an open
universe. In both cases, our results agree with observations and show
that hierarchical scenarios provide a good model for structure
formation and can describe a wide range of objects which spans at least the
seven orders of magnitude in mass for which data exist. More detailed
observations, in particular of the clustering
evolution
of galaxies, will constrain the astrophysical models involved.

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